The present invention relates to a new and improved construction of a drive control for an elevator or the like.
Generally speaking, the drive control of the present development for an elevator or other transport systems comprises a regulation circuit composed of a velocity regulation circuit, a position regulation circuit, at least one pulse transmitter operatively associated with an actual value transmitter of the position regulation circuit, and at least one digital-analogue converter (D/A-converter). Additionally, there is provided a reference value transmitter which generates a group of travel curves. The reference value transmitter possesses a control storage which contains at least permissible jolt or jerk values and threshold values of the acceleration and which is connected with three summation stages which generate the acceleration, the velocity and the path by continuous numerical integration. The output magnitudes of the last summation stage are infeed to the regulation circuit as displacement path-reference value, and for the determination of the braking application point there is provided a stop initiation device which produces a stop initiation signal and coacts with the control storage and a storey site storage.
In German Pat. No. 1,302,194 there has been disclosed such type of drive control. Here, the determination of the braking initiation point, and thus, the possible halt or stop point, is accomplished by continuous computations during the acceleration phase while utilizing a digital computer. The computation is predicated upon considering the geometric conditions of the momentary velocity travel curve. The area below the travel curve, corresponding to the reference value, is converted in the velocity-time diagram into a trapezoidal area or surface whose first boundary line coincides with the velocity axis and whose second boundary line extends parallel thereto. The intersection point of the second line with the travel curve constitutes the brake application or initiation point. The length of the first boundary line corresponds to an initial velocity v.sub.ho, whereas the slope of a third, upper boundary line corresponds to an acceleration b.sub.h. From these values stored in a control device, there is formed in a first integrator the velocity and in a subsequently connected second integrator a possible stop or halt path s.sub.halt. In a comparison device this path is compared with a target path s.sub.targ set at a target position transmitter and corresponding to a storey for which there has been stored a call. When s.sub.halt =s.sub.targ the comparison device or comparator generates a signal, causing the control device to initiate the deceleration by delivering threshold values for jerk and deceleration movements to three further, series connected integrators. The reference value s.sub.ref generated in the third integrator is infed to a position regulation circuit. A counter, which counts the pulses of a pulse transmitter driven by the drive machine, forms the actual path s.sub.act, which likewise is infed to the position regulation circuit.
With this drive control it is possible that due to the stepwise generation of the travel curves the halt path s.sub.halt and the reference path s.sub.ref, respectively, do not correspond with the target path s.sub.targ, so that there result stop or halt inaccuracies. Furthermore, the deviations, resulting from cable slip and elongation, between the actual elevator cabin path and the actual path determined by the pulse transmitter and counter, cannot be detected, so that also in this case, depending upon the displacement path length and weight, there can arise rather extensive halt inaccuracies. The technique of continuous computation of the possible halt path, employed with this drive control for the purpose of determining the brake initiation or application point, requires appreciable computations, and thus, corresponding computer capacity, something which is unfavorable from the standpoint of the economy of the system. The use of a second D/A-converter, needed because of the incorporation of the velocity-reference value in analogue form into the velocity regulation circuit, results in additional costs.